Electrics D C
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(In Topic #12084)
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Using either 9 volt or 12 volt plug in adaptor
Hi All. I have a choice of adaptors, either 9 volt DC or 19 volt DC , as these are obosolete from a radio or WHY I thought either of them could be used to power a "separate DC LED circuit on my layout". So I set off for my local Maplin electrical store, where I asked about a suitable socket, all I got were blank faces and gobbledygook .Now I am turning to the forum for help, Straight forward ? Any advice please. Kevin
Staying on the thread Kevin.
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cut the plug off and terminate the wires onto a terminal strip -
http://www.maplin.co.uk/p/30a-terminal-strip-12-way-3-pack-n66eg
use the 9v unit for LEDs with say 500 ohm resistors
http://www.instructables.com/id/LEDs-for-Beginners/
Ron
NCE DCC ; 00 scale UK outline.
NCE DCC ; 00 scale UK outline.
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http://www.originlive.com/magento/media/catalog/product/cache/3/image/800x600/9df78eab33525d08d6e5fb8d27136e95/u/k/uk_1.jpg
wall wart
http://au.rs-online.com/largeimages/R4649744-01.jpg
terminal strip
You will need to either connect a number of LEDs in series, or add a resistor in series with LEDs, as 9V would probably blow a single LED connected directly
EDIT - oops great minds think alike!
Last edit: by Dorsetmike
Cheers MIKE
I'm like my avatar - a local ruin!
I'm like my avatar - a local ruin!
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Staying on the thread Kevin.
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Staying on the thread Kevin.
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, but do not forget the resisters
:thumbs ;-) :cool:
web-cam 2.2.74.174:8081
if the lights are off no cam
if the lights are off no cam
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Staying on the thread Kevin.
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If the resistors are the right size, then it doesn't matter if they are wired back to front. If it's a DC supply, then the worst thing that can happen is that the LEDs won't light. Then just swap the leads over.
If it's an AC supply (like your DCC track power), then the polarity isn't an issue.
Max
Port Elderley
Port Elderley
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Test the output from the transformer to make sure you know your anode from your cathode (and the actual voltage). The anode on a regular LED is the longer wire. Cathode is the shorter one on the flat side. It doesn't matter which side the resistor goes. It's worth while getting a selection of resistors to determine what light intensity you want.
If you use the 19v transformer something near 1000 ohm might be more appropriate.
What color(s) are you going for?
Nigel
©Nigel C. Phillips
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Staying on the thread Kevin.
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Nothing wrong with a battery if you only have a few LEDs. 4 LEDs in series and you won't need a resistor (4 x forward voltage will be about 9v). Pop a reed switch into the circuit and you won't need to keep disconnecting the battery.
Nigel
©Nigel C. Phillips
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See the link
http://www.hobby-hour.com/electronics/ledcalc.php
Ron
NCE DCC ; 00 scale UK outline.
NCE DCC ; 00 scale UK outline.
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Which does sound simplistic? to say the least. Reading that, sounds like the lamps can be wired in parallel?
But I believe that the lamps with a 12v supply may be very bright. all the best. Kevin
Staying on the thread Kevin.
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Staying on the thread Kevin.
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. Reading that, sounds like the lamps can be wired in parallel? YES
But I believe that the lamps with a 12v supply may be very bright. Try them and see but I doubt it as the resistor reduces voltage so the LED get only 2-3v
Ron
NCE DCC ; 00 scale UK outline.
NCE DCC ; 00 scale UK outline.
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Hi Ron,Nigel, I had read that a LED requires a resistor in 99% of the time & the value depends on supply voltage, LED volts and current.
See the link
http://www.hobby-hour.com/electronics/ledcalc.php
Yes….but only if there is an initial surge. Works best with the circular Li batteries (inherent internal resistance), or good (brand-name) AA's (especially the Li-polymer ones coming onto the market). Depends on the LED color as that is what governs voltage drop and current requirements. White ones need a lot more than red or green. If in doubt use a limiting resistor of around 220 ohm with a battery.
Kevin, it looks like you have a RTR solution. If each lamp has it's own resistor then you should have no problems in running them in parallel as every one will get 9-12V. The only issue is that for example 20 with a current draw of 20 mAmp each will require at a minimum a 400 mA supply. I can see why you would want to drop to 9V if they are too bright.It's easier to use a resistor with more ohms to change the light intensity.
A 9v battery has a capacity of around 500 mAh at best, a yellow platform lamp will draw around 20 mA, 5 lamps will last 5 hours or less (probably 3 hours). If you go the battery route it's worthwhile using rechargeable ones (if only for the environment). Best bet is still a small transformer (9V, 0.6 Amp would be OK and leave some spare capacity and will cost around £7.00).
Nigel
Nigel
©Nigel C. Phillips
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Staying on the thread Kevin.
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Now if you don't know how to use a multimeter ( an essential tool in this hobby ) http://www.ehow.com/how_8516583_use-multimeter-beginner.html
Ron
NCE DCC ; 00 scale UK outline.
NCE DCC ; 00 scale UK outline.
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Ron
NCE DCC ; 00 scale UK outline.
NCE DCC ; 00 scale UK outline.
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Staying on the thread Kevin.
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